1. Field of the Invention
The present invention relates to an intake muffler duct for motor vehicles which guide air to the motor vehicle engine as well as reduce the intake noise.
2. Description of the Prior Art
The intake duct which supplies air to the engine of a motor vehicle is equipped with an intake muffler in order to reduce the intake noise, and with regard to such intake mufflers there are expansion type mufflers, Helmholtz type mufflers, side branch type mufflers, etc. Since it is difficult to reduce the intake noise in all frequency regions using a single intake muffler, multiple intake mufflers each of which reduces the intake noise in a specific frequency range are combined so as to reduce the intake noise over a wide frequency range (see for example Japanese Patent Application Laid-open No. 4-318269).
However, since an engine and a large number of accessories are placed in the motor vehicle engine compartment, it is difficult to ensure that there is space to install multiple intake mufflers. In addition, if multiple intake mufflers are installed independently, the number of components, the number of processing steps and the number of assembly steps increase, resulting in an increase in cost.